This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my two applications both entitled TENSION MASK FRAME ASSEMBLY OF COLOR PICTURE TUBE filed with the Korean Industrial Property Office on Apr. 20, 2000, and there duly assigned Ser. No. 20992/2000 and 20993/2000, respectively.
1. Technical Field
The present invention relates to a color picture tube, and more particularly, to a tension mask frame assembly for a color picture tube in which the structure of a tension mask fixed to a frame is improved.
2. Related Art
In a color cathode ray tube (CRT) or color picture tube, an electron beam emitted from an electron gun passes through an electron beam passing hole of a tension mask and lands on a fluorescent film so that a fluorescent film is excited to form an image. A surface of a screen of a color picture tube where an image is formed is designed to have a predetermined curvature considering a trajectory of the electron beam emitted from the electron gun and deflected by a deflection yoke.
When the mask manufactured to have a curvature corresponding to the inner surface of the screen is heated by the electron beam emitted from the electron gun, that is, by thermions, a doming phenomenon in which the mask is bulged toward a panel occurs. The doming phenomenon prevents the electron beam from accurately landing on the fluorescent film. Also, since the screen surface is formed to have a predetermined curvature, a viewing angle is narrow and the fluorescent film is excited at the edge of the screen surface so that an image formed at the screen surface is deformed.
We have found that it can be difficult to design and manufacture an improved high quality tension mask frame assembly for color picture tube. Efforts have been made to improve color picture tube components.
Exemplars of recent efforts in the art include U.S. Pat. No. 4,926,089 for TIED SLIT FOIL SHADOW MASK WITH FALSE TIES issued to Moore, U.S. Pat. No. 4,942,332 for TIED SLIT MASK FOR COLOR CATHODE RAY TUBES issued to Adler et al., U.S. Ser. No. 09/461,758, now U.S. Pat. No. 6,472,806 and U.S. Ser. No. 09/465,763, now U.S. Pat. No. 6,437,496.
While these recent efforts provide advantages, I note that they fail to adequately provide a tension mask frame assembly for color picture tubes efficiently and conveniently reducing problems associated with the related art such as deformed images and dotted line smear problems.
To solve the above problems, it is an object of the present invention to provide a tension mask frame assembly of a color picture tube which can reduce generation of dotted line smear appearing on a screen of the tie bars and the dummy bridges due to a difference in the amount of light of an electron beam passing between the dummy bridges according to the incident angle of the electron beam.
Accordingly, to achieve the above object and others, there is provided a tension mask frame assembly for a color picture tube comprising a tension mask where a plurality of strips formed on a thin plate to be separated a predetermined distance forming slots, a plurality of tie bars for connecting the strips and sectioning the slots at a predetermined pitch, and a plurality of dummy bridges extending from at least one strip toward a facing strip in the slots sectioned by the tie bars, and a frame supporting the edge of the tension mask while tension is applied to the tension mask, in which the area of the dummy bridge of the tension mask gradually gets smaller from the central portion of the tension mask to the peripheral portion of the tension mask.
It is preferred in the present invention that the vertical length of each of the dummy bridges at the central portion of the tension mask is greater than the vertical length of each of the tie bars, and that the vertical length of each of the dummy bridges at the peripheral portion of the tension mask is the same as the vertical length of each of the tie bars.
To achieve the above object and others, there is provided a tension mask frame assembly for a color picture tube comprising a tension mask where a plurality of strips formed on a thin plate to be separated a predetermined distance forming slots, a plurality of tie bars for connecting the strips and sectioning the slots at a predetermined pitch, and a plurality of dummy bridges extending from at least one strip toward a facing strip in the slots sectioned by the tie bars, and a frame supporting the tension mask while tension is applied to the tension mask, in which the tension mask includes a uniform dummy bridge area portion in which the area of each of the dummy bridges is uniform in a direction toward the peripheral portion of the tension mask and a decreasing dummy bridge area portion in which the area of each of the dummy bridges gradually decreases from the uniform dummy bridge area portion to the peripheral portion of the tension mask.
It is preferred in the present invention that, given that the horizontal length of the tension mask is H, a boundary between the uniform dummy bridge area portion and the decreasing dummy bridge area portion is located at a position displaced by xc2x1H/6 of the horizontal length of the tension mask from the central portion of the tension mask 60 in an X direction.
Also, it is preferred in the present invention that the vertical length of each of the dummy bridges disposed at the decreasing dummy bridge area portion gradually decreases as the dummy bridges are located closer to the peripheral portion of the tension mask, and that the area of each of the dummy bridges located at the outermost position of the peripheral portion of the tension mask is formed to be the same as the area of each of the tie bars.
To achieve the above object and others, there is provided a tension mask frame assembly for a color picture tube comprising a tension mask where a plurality of strips formed on a thin plate to be separated a predetermined distance forming slots, a plurality of tie bars for connecting the strips and sectioning the slots at a predetermined pitch, and a plurality of dummy bridges extending from at least one strip toward a facing strip in the slots sectioned by the tie bars, and a frame supporting the tension mask while tension is applied to the tension mask, in which the area of the dummy bridge at the central portion of the tension mask is greater than the area of the dummy bridge at the peripheral portion of the tension mask.
To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides a tension mask frame assembly apparatus for a color picture tube, the apparatus comprising: a tension mask forming a plurality of strips on a thin plate, a plurality of slots, a plurality of tie bars connecting said strips and sectioning said slots at a predetermined pitch, and a plurality of dummy bridges extending from at least one strip toward an adjacent strip in said slots, said strips being separated a predetermined distance by said slots, said tension mask having a central portion and having a plurality of edges; and a frame supporting said edges and applying tension to said tension mask, an area of each of said dummy bridges near said edges being less than an area of each of said dummy bridges at a central region of said tension mask.
To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides an apparatus, comprising: a tension mask including a plurality of strips formed on a thin plate and separated a predetermined distance by slots, a plurality of tie bars connecting said strips and sectioning said slots at a predetermined pitch, and a plurality of dummy bridges extending from at least one of said strips toward an adjacent one of said strips in said slots; and a frame supporting said tension mask and applying tension to said tension mask; said tension mask including a centrally-located uniform dummy bridge area portion in which the area of each of said dummy bridges is uniform, said tension mask including a decreasing dummy bridge area portion in which an area of each of said dummy bridges gradually decreases in a direction from said uniform dummy bridge area portion to a peripheral portion of said tension mask.
To achieve these and other objects in accordance with the principles of the present invention, as embodied and broadly described, the present invention provides a tension mask frame assembly apparatus for a color cathode ray tube, the apparatus comprising: a tension mask having a plurality of strips formed on a thin plate and separated a predetermined distance by slots, a plurality of tie bars connecting said strips and sectioning said slots at a predetermined pitch, and a plurality of dummy bridges extending from at least one of said strips toward an adjacent one of said strips in said slots sectioned by said tie bars; and a frame supporting said tension mask and applying tension to said tension mask, an area of one of said dummy bridges located at a central portion of said tension mask being greater than an area of one of said dummy bridges located at a peripheral portion of said tension mask away from said central portion.
The present invention is more specifically described in the following paragraphs by reference to the drawings attached only by way of example. Other advantages and features will become apparent from the following description and from the claims.